A drug currently used to treat Alzheimers disease has shown promise in clinical trials as a treatment for patients with traumatic brain injuries.
The drug, rivastigmine, works by boosting the levels of a chemical messenger in the brain involved in memory and learning.
Jonathan Silver at New York University School of Medicine, US, and colleagues recruited 134 patients with brain injuries at 19 centres around the country and divided them into a treatment group and a placebo group.
Patients in the treatment group took a minimum dose of 1.5 milligrams of rivastigmine per day, which was increased to 6 milligrams per day if patients could tolerate it side effects included nausea, cold symptoms and headaches.
After 12 weeks, researchers assessed learning, memory, recognition, attention, problem solving and long-term recall.
Severely or moderately impaired patients taking rivastigmine showed significantly improved scores compared to those on placebo. In practical terms, this meant that patients felt that things were "clearer" and they were less forgetful. They also said that the drug made them feel less bothered by many things going on around them at once.
With an estimated 1.5 million people suffering from traumatic brain injury each year in the US, rivastigmine shows promising results for these patients with moderate to severe memory loss, says Silver. Many traumatic brain injuries are sustained in traffic accidents.
Rivastigmine is a type of cholinesterase inhibitor it blocks the breakdown of a brain chemical called acetylcholine. Previous work has suggested that acetylcholine enhances memory function by boosting the activity of neurons and synapses the connections between neurons in the cortex in response to new information being learned.
Alireza Atri, at the memory disorders unit at Massachusetts General Hospital in Boston, US, says the study is encouraging and he would have expected a stronger response, but for the fact that the patients were neuropharmacologically "dirty", meaning that the patients were already taking other brain-affecting drugs and this was not controlled for.
But this does not preclude therapeutic use of cholinesterase inhibitors, he says. Atri also emphasises that the timing of treatment is an important factor. In this study, the average elapsed time since injury was six years. Youd expect increased efficacy if the treatment was given sooner, Atri says.
Michael Hasselmo, at the Center for Memory and Brain at Boston University, Massachusetts, says that the study is encouraging for showing the potential benefit of rivastigmine. Even in normal subjects, he says, blocking acetylcholine receptors has been shown to impair memory, and boosting acetylcholine has been shown to enhance memory.
Journal reference: Neurology (vol 67, p 748)